When do I remove the paper towels?

Hey everyone, my babies are now 8 days old. I started off putting their feed in piles throughout the brooder (for about 4 days) Then yesterday I put down 2 feeders (full) and scattered feed in front of them. Did the same this morning.
I am wondering when it wil be ok to remove the paper towels and use the pine shavings alone. The mess is getting to be a bit...how ya say....overwhelming.
Thanks